Allfat

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Hello,

So I have a Sig 4*40 that I want to change the engine to a four stroke. There are a couple on consignment at the LHS and I was wondering if they are good deals and would they be good matches for the 4*40.

First, there is a OS 48 FS for $100. This engine looks like it has been run quite a bit, and is a bit dirty on the outside.

Second is an OS 52 FS for $175. The catch is that it comes with a plane, lol. The plane that it comes with looks like it would be fun and it comes with 9 servos (split ailerons, flaps, spoilers, elevator, rudder, & throttle) as well as everything to make it into a flyable plane with the addition of a receiver. However, if I buy this plane, then I would still not have an engine for the 4*40, and I am not really looking for a new plane right now.

I have also looked at buying a Saito 56 for $230 new, but I am trying to keep cost down.

So what do you think about these engines with the 4*40 airplane. Would the 48 FS be enough to haul it around and be aerobatic, and will the difference between the 48 and the 52 be worth it, and would it be worth it to spring for the new, larger four stroke of all my options, or is there another engine that I should be looking at that is better than all of these? Please help me out here because I am sort of lost. Thank you.

stang

My Feedback: (1)

For my two cents worth: I wouldn't touch a used engine. Some have success with it but I've seen too many bad ones too take that chance. I think that all those engines you mentioned are too small for the 4 *. I wouldn't go less than a 70 four stroke. You really need the power.

ChuckW

I'm not sure about the .48 but the .52 or .56 will fly the 4* pretty well. It won't be ballistic or anything but still enjoyable if it is propped right.

Used engines can be a gamble. If you are willing to possibly replace a bearing or adjust the valves, etc. though, you could score a good deal.

jship

My Feedback: (4)

With no experience with four strokes, Your asking for problems.. You could end up buying someone else’s and making it You problem. I’ve seen people do it many times to save $50.00.

MetallicaJunkie

i agree for balls out performance i would go with a 90 4s, and for the 60 size id go with a 120 4s, i myself have a super tigre 90 on my 4* 60 and its awesome, its my super relaxed, stress free, care freel flying airplane

w8ye

My Feedback: (16)

There's not a significant difference in power between a good OS 48 and a OS 52. The Saito 56 has more noticeable than a OS 52.

But a ratty looking engine is a ratty engine. Buy something else.

I have four OS 52's and used to have a OS 48. Most of the parts will interchange on these two engines except for the crankshaft/crankcase.

I have 3 Saito 56's among other engines. I think the 56 is a lot more engine.

Any of these engines will fly your plane through loops and rolls

Allfat

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Well, you guys have convinced me that new is the way to go on an engine, so that gives me a good start. Thanks for all the advice guys!

Andrewmc

I have a Saito 56 on my 4* 40 along with several other recent 4* flyers. It does not have unlimited vertical, but that is not what I am looking for. With a 12x6 prop on it has a great turn of speed at full throttle and still can slow down nicely for landing.

If I was to build another 4* I would put in another Saito 56!

Allfat

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This is what I like to hear, first hand accounts of how different engines work with this plane. I like the way that Saito 56 sounds as that is what I am going for in this plane. Thanks Andrewmc!

Jetdesign

My Feedback: (8)

I'm darn near ready for my first four stroke - it's killin' me! I got this 9lb Yak54. Saito125 ain't quite gonna cut it, at least for my style. OS120 Surpass - heavy and slow, that's bein' saved for the Sunday flier I'll never own. YSFZ110-s - now THATS and engine. Power, sound, technology... but the darn cost of fuel for these things, and the learning curve KISS tells me to stay away from. Where's the 140FS-a??? What does this all spell out? O-S-1-2-0-A-X. Guess I have to wait another year[:@] Honestly, with that engine, I got nothin' but love

Sandmann_AU

I know a lot of people bag the ASP/Magnum engines, but I've got an ASP 120 FS that's been nothing but excellent. It starts with a flick of the prop and hauls around my (kit built, therefore heavy) super skybolt effortlessly, with practically unlimited vertical. Granted, not as much power as an OS Surpass but at half the cost too. It even survived a direct nosedive into the ground at full noise without bending the crank.

Just remember that a 4 stroke will require a little more maintenance than a 2 stroke - you do have to adjust the valves periodically, and the glow plugs are slightly more expensive. However they use less fuel than a 2 stroke, turn bigger props, and have smaller mufflers.

Matt

Clay Walters

I'm relatively new because I returned to the hobby after many years away. Having told myself that when/if I ever get back in I'm going to try a four-stroke; I did. Purchased a new Magnum XL 91 RFS this past Spring.

I'd also mentally prepared myself to have to tinker with it because my memory was that 4-strokes were cantankerous. The booger fired up on the very first try! And ran like a top.

The only thing I've had to fiddle with as a result of going 4-stroke is the placement of the throttle and the direction of actuation.

I've acquired two more Magnum 4-strokes but haven't taken them out of their boxes yet. Based purely on the comments above I'd be very tempted to try a Magnum XL 70 RFS on a 4-star. It has some of the newer features regarding crankcase venting and carburetor placement that make it appear attractive. They also had a batch of them get out with the wrong valve springs that tainted its reputation. I feel that if I were to purchase a brand new one today there's a really good chance it will be a top-notch engine.

And for the prices you mention there's no way I'd consider a used or older one.

Regards,

Clay

Rudolph Hart

Stick an 82 in it

ChuckW

I wouldn't rule out a 1.25 on a 9 pound airplane. Heck, I've got a .91FS on a Mustang in that weight range and it is plenty fast. It won't go vertical into orbit but it is still respectable. A 1.25 would really be wild, especially if propped right and tuned well.

Same goes for the OS 1.20. Yes, it's a little on the heavy side compared to some others but it runs excellent with decent power.

YS? They make great power. The trade-off is a slightly more complicated fuel system set up and some people find them a little more difficult to tune. Nothing wrong with that of course but just saying that there is usually a negative for every advantage.

Your 1.20AX 2-stroke is a fine engine too and will get the job done.

My point is, until you've owned these engines and seen what they can do first hand, you won't know exactly what they will and won't do. Power specifications used in adds are meaningless. Hearsay at the field or online is sometimes accurate but sometimes not. Try one for yourself, then decide.

bigtim

My Feedback: (13)

the saito 125 will haul a 10-12lb plane just fine the OS 120 has loads of power as well, just because a engine isn't loud doesn't mean its not powerfull with a 15/4- 15/6 prop it will drag that 9lb. YAK around.

really a good rule of thumb is the 20-30 rule with 4strokes if your powering a plane with a 46-55 2stroke then a 70-82 4stroke would be a solid powerplant.
likewise a 60-75 2st a comparison is 91-100 4st.
and for the 90-120 2st would be a 120-140 4st.
its just a aprox.comparison but the ratio works,for YS engines drop 10 points there freaky powerfull, at the expense of 20/20 fuel.

PipeMajor

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I have an H9 UltraStick 40 with a Saito .62 and a Sig 4*60 with Saito 1.00

w8ye

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I have a couple Ultra Sticks with Saito 56's

Gray Beard

My Feedback: (-1)

Yep, those OS 1.20s are heavy and under powered. I guess this old 16 pound scratch built Boeing F4B-2 with the OS 1.20 pumper will never get off the ground and do a stunt. I have the same engine in a 68 inch Extra and the same plane with A YS 1.20, truth is the YS has more power but no one would ever notice except the pilot. As to a used .48, not a chance, that is an older engine and you would never know it's history so you would want to go through it and do a rebuild. The going price for a .48 is about 50 bucks so it comes out to a hundred dollars after the rebuild. More work and risk buying the used one without a lot in savings.

ChuckW

Yeo Gene, those OS 1.20 4-strokes are worhtless. That plane can't possibly fly.

Jetdesign

My Feedback: (8)

Maybe I've been getting too polluted from pattern and IMAC forums. I would absolutely LOVE to have an OS 120 four stroke in my new Yak and be happy with it. Having such little experience I don't know how spoiled I am with my 120AX though; Venus II is a 9lb plane and I wouldn't want any less power. I'd hate to spend $400 and be disappointed when I could spend $270 and be content.

w8ye

My Feedback: (16)

Be proud of your 120AX they are fine engines and a much newer design than the OS 120 four stroke which came out 20 years ago as a redesign of the old double rocker 120 in the same form it is today with complete parts interchangeability

Gray Beard

My Feedback: (-1)

Your 1.20 AX is an outstanding engine and there is no way I would ever give the money they are asking today for any of the four strokes. I haven't seen the prices on the YS engine in a long while but I'm sure they have been raised too. I have a couple of the OS 1.20 and a .91 but these were given to me and I just rebuilt them. Joe, at this point in time you should stick with what works for you and the AX line is doing just that. I'm sure all you hear from pattern guys is the only four stroke worth owning is the YS but there is nothing wrong with OS and Saito other then the price. I do love my YS engines though A lot!!!!

ChuckW

Nothing wrong with that. Use what you like and what you are comfortable with. It's not like you made a lousy choice or anything; that 1.20 2-stroke is sweet. Just don't rule anything out completely until you've given it a shot and seen first hand what it will or won't do.

Jetdesign

My Feedback: (8)

If I wasn't so driven by competing I'd strap an OS four stroke in a plane in a heart beat. With Tower's super saver discounts, free shipping, and the rebate it's really not all that bad considering the cost of the competition. YS 110 is $369 and is really pulling at me from all directions. 120Ax is absolutely amazing, and is more competitive against the YS 110 than both the Saito 125 and the OS 120 four stroke.

If I make an intelligent decision, I'll buy another 120AX (and a couple of cases of fuel!), but if I end up giving in to the sound, torque, and just plane neat factor of a four stroke I'll get the YS 110. Meanwhile I'll keep reading threads like this for a reason to just get a four stroke and forget about it

Gray Beard

My Feedback: (-1)

My YS 1.10 was selling for 350 four or five years ago. I either paid 310 or 325 but it was on sale at a big hobby shop in Sacramento. So the 370 today isn't a big jump. As to the true flying of a plane there isn't enough difference between your AX or the YS 1.10. I built an Extra just like mine for a friend and we installed a new YS 1.40 Sport and it flew the plane quite a bit better then mine with the YS 1.20 NC. or the OS 1.20, a lot better. A lot will always depend on the plane every bit as much as the engine. I'm working on an old Daddy Rabbit right now that won the 1966 Nats Pattern and it did it with A Clarence Lee .61 K&B. Back then they had stringent rules about engine size, this was the old turn around pattern. I'm building the plane to the plans and keeping it old school but using a SK .91. I'm not near the pilot as these guys were so I need all the power I can get to help make me look good. What does this have to do with the OP question??? Nothing, it was answered and we are just shooting the breeze.